One of the steps employed in manufacturing of carpets using synthetic materials such as nylon or polypropylene is to subject extruded strands of the yarn material to a "texturizing" process wherein the strands are caused to become highly kinked throughout their length so as to impart resilience and body to yarns incorporating the strands. Texturizing is typically carried out by feeding an array of a large number such as 57 strands across a series of rollers and through a vertically disposed texturizer device at a high-speed such as 103 feet per second and at an elevated temperature such as 180.degree. F. The texturizer is generally in the form of a rectangular block having a longitudinally extending central aperture varying in diameter at various locations to provide for a narrow input region, expanded nozzle region, and an enlarged exit region. Texturizing in such devices is initiated by momentarily blocking the outlet, deceasing the tension at which the strands are held, the resulting slack allowing the strands to undergo extensive kinking in the expanded nozzle region. This kinking effect is retained as a "memory" in the resulting yarn, into which the strands are incorporated after the yarn is wound onto and passed through a further series of reels or rollers for further processing.
A widely used prior art texturizer 10 is shown in FIG. 1 of the drawings. The texturizer is in the form of a rectangular block made up of two mating halves and having a longitudinally extending central aperture 12. The aperture has a relatively small diameter at a top input region 14, a larger diameter region 16 traversing its middle and located below compressed air inputs 18, a downwardly expanded conical nozzle region 20, and an enlarged exit region 22 at the bottom. Heated compressed air is introduced through apertures 24 in the block that communicate with inputs 18 to the central aperture through passageways 26. The inputs 18, a total of four being provided, are all located at the same axial position in relation to the central aperture, and the compressed air introduced therethrough provides a balanced force against the strands, without producing a significant swirling motion that would twist the strands around one another. In addition, swirling motion is prevented by introducing the air through passageways that are disposed at a small angle such as 10.degree. to 12.degree. with respect to the central bore. Yarns that are texturized by use of such a device require an additional process step known as "air entanglement" in order to obtain twisting as well as kinking in the product yarn. Provision of a texturizer that produces twisting, along with kinking, action would be highly advantageous.
Available texturizers as shown in FIG. 1 also have presented a problem in that the mating halves of the block have tended to become warped and separated from one another in use, allowing some of the strands to enter into the space between halves and become snagged or torn, thus reducing the quality of the yarn product. The snagged or torn strands upon moving downward also may cause the kinked material to become matted, plugging up the aperture and halting production. Prior texturizers of this type have generally been made of soft steel to permit easier fabrication, and the mating faces of the two halves have been forced together by air pressure and designed with a slight bow to compensate for warping, but the problem has persisted.